Merge pull request #2628 from edx/jibsheet/revert-pr2586

We still need to coerce into a string

playbooks/library/util_map

@@ -159,7 +159,7 @@ def main():
 
     arg_spec = dict(
         function=dict(required=True, type='str'),
-        input=dict(required=True),
+        input=dict(required=True, type='str'),
         args=dict(required=False, type='list'),
     )